P0339Powertrain
Powertrain · SAE
CKP Sensor — Intermittent
Meaning
The engine control module has detected that the crankshaft position (CKP) sensor signal disappears and reappears irregularly during engine operation. The intermittent signal loss can cause misfires, sudden stalls, or sporadic no-start conditions.
Common causes
- Loose, corroded, or intermittent CKP sensor connector
- Wiring harness with partial or intermittent break (cable flex point)
- Reluctor wheel with localized dirt or deposits periodically interrupting the signal
- CKP sensor with internal intermittent failure (temperature or vibration sensitive)
- Intermittent ground fault on the sensor or ECM
- Sporadic electromagnetic interference from other vehicle circuits
Symptoms
- Check-engine light (MIL) on intermittently or continuously
- Sporadic misfires or power loss while driving
- Engine stalls without warning with possible restart
- Fault worsens with high temperature or vibration
- In some cases no perceptible symptom at time of diagnosis
Severity
High: intermittent CKP faults can cause sudden stalls while moving; the fault typically worsens over time until complete failure occurs.
What to do
- Wiggle the wiring and connector during live-data monitoring to reproduce the fault
- Inspect the CKP sensor connector for loose pins, corrosion, or moisture ingress
- Check the harness along its entire route for chafe points, kinks, or crush damage
- Clean the reluctor wheel of any localized deposits
- Replace the CKP sensor and connector if the intermittent fault is confirmed on inspection